JPH04110219U - Structure to prevent shaft vibration of rotating shaft - Google Patents

Abstract

(57) [Summary] [Structure] In the electromagnetic limited rotation electric motor 1, the outer peripheral portion of the rotor 33 is formed of a permanent magnet 31. A permanent magnet member 38 is attached to the stator 34 side. In operation, the rotor 33 is constantly attracted by the permanent magnet member 38 by magnetic attraction force. This attractive force constantly acts on the rotor as a radial biasing force to prevent the rotary shaft from wobbling during rotation. At the same time, this suction force acts as a return force for returning the rotor to its original position. [Effect] The simple configuration of attaching a permanent magnet can prevent the shaft runout of the rotating shaft.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention relates to a shaft vibration prevention structure for preventing shaft vibration of a rotating shaft. It is.

0002

[Conventional technology]

In order to prevent the shaft from wobbling, an elastic member is used to move the shaft in the radial direction. A mechanism is adopted that biases the For example, in an electromagnetic limited rotation electric motor, Generally, driven parts require high response speed and accurate rotational positioning accuracy. Since it is used as a drive source for parts, it is necessary to prevent the rotor from wobbling. Ru. A rotor is generally rotatably supported by bearings at both ends of its rotating shaft. held. Ideally, the rotor's central axis of rotation should not swing in the radial direction. It is desirable that it be supported as such. However, manufacturing errors in bearings and assembly The rotor may be slightly displaced in the radial direction due to misalignment, etc. is in a state. For this reason, the rotating shaft vibrates in the radial direction with rotational motion. A movement occurs.

0003

[Problem that the idea aims to solve]

If such contact of the rotating shaft occurs, the accuracy of detecting the rotational angular position of the rotor will decrease. In some cases, the rotor may be lowered, making it impossible to accurately position the rotor. The challenges of this invention are: We have realized a shaft vibration prevention structure that can prevent shaft vibration of the rotating shaft with a simple configuration. be.

0004

[Means to solve the problem]

In order to solve the above problems, the shaft vibration prevention structure of the present invention has at least A rotating shaft whose circumferential surface is partially made of a magnetic material, and this rotating shaft are at least bearing means rotatably supported over a certain angular range, and a rotating shaft. A permanent magnet placed on the outer periphery opposite the part made of magnetic material. It is made up of a magnetic member, and uses the magnetic force of this permanent magnet member to rotate. The rotating shaft is biased in the radial direction.

[0005] Here, the outer periphery of the rotating shaft facing the permanent magnet member may be used as a permanent magnet. stomach. In addition, the magnetic force generated between the rotating shaft and the permanent magnet member is a repulsive force or It can be any type of suction power. If the suction force is generated, this suction The force can be used as a return force to return the rotating shaft to the installation position of the permanent magnet member. Ru.

[0006]

[Effect]

In the shaft vibration prevention structure of the rotating shaft of the present invention, the permanent magnet member and the rotating shaft are Due to the magnetic force generated between them, rotational force is constantly applied in the radial direction. Okay This prevents the shaft from running out. Also, a magnetic attraction force is generated. In some cases, the rotating shaft can be permanently moved to the origin position without using a torque spring or the like. The magnet can be returned to its installed position.

[0007]

【Example】

Embodiments of the present invention will be described below with reference to the drawings.

[0008] Figures 1 and 2 show an electromagnetic system using the rotary shaft vibration prevention structure of the present invention. FIG. 1 is an external perspective view and a vertical cross-sectional view of a limited rotation type electric motor. The electric motor 1 in this example is , a motor main body 3 and a position sensor 4 are coaxially arranged inside a cylindrical case 2. It has a built-in configuration. The motor main body 3 has an outer circumference of the rotating shaft 31. At its center is a rotor 33 consisting of a cylindrical permanent magnet 32 fixed to the are doing. A cylindrical hard disk is installed so as to surround the outer periphery of the permanent magnet 32 of this rotor 33. A constantr 34 is attached concentrically. The rotating shaft 31 of the rotor 33 is permanently At the base end side and the tip side protruding from the magnet 32, a ball bearing is attached. Rotates around the central axis 33a with respect to the case 2 via 35 and 36 It is supported in a state of freedom. The tip end portion of the rotating shaft 31 is a ball bearing. It passes through the center of the ring 35 and the position sensor 4, and rotates from the front end surface 21 of the case. It protrudes as a rotation output shaft 31a.

[0009] FIG. 3 is a cross-sectional view of the electric motor, and with reference to this figure, the inside of the electric motor main body 3 Explain the structure. First, the permanent magnet 32 has both ends in the diametrical direction of its cylindrical cross section. It has a north pole magnetic pole surface 32N and a south pole magnetic pole surface 32S. On the contrary, A pair of magnetic poles are provided on the inner peripheral surface of the stator 34 and extend toward the center of the cylindrical cross section. Portions 341 and 342 are formed. These magnetic pole parts pass through the rotation axis 33a. It is formed along the diameter direction, and is almost the same as the permanent magnet 31 on the rotor side. It has an axial length. At the tips of these magnetic pole parts 341 and 342, permanent A magnetic pole surface 341a having an arc shape with a radius slightly larger than the outer peripheral surface of the permanent magnet 31 , 342a are formed. These arcuate surfaces are connected through a certain gap , facing the outer peripheral surface of the permanent magnet 31. These magnetic pole parts 341 and 342 Field windings 343, 3 are provided on the outer periphery for generating rotor driving magnetic flux, respectively. 44 is wrapped around it. Both ends 345 and 346 of the field winding are connected to the power supply line 37 and a drive power source (not shown) via a magnetic flux control circuit (not shown). It is. A commonly used magnetic flux control circuit can be used. Since it is possible, the explanation will be omitted.

0010 Here, on the inner peripheral surface of the stator 34, the pair of magnetic pole parts 341, 34 2, a permanent magnet member 38 is fixed at an angularly intermediate position. . This permanent magnet member 38 has approximately the same axial length as the permanent magnet 31 on the rotor side. It has a certain quality. In this example, the magnetic pole of this magnet is directed toward the rotation center axis 31a. The surface facing the rotor side is the north pole magnetic pole face 38N, and the fixed The surface fixed to the child side is the S-pole magnetic pole surface 38S.

[0011] Next, the configuration of the above-mentioned position sensor 4 will be explained with reference to FIGS. 4 and 5. . This position sensor 4 is an optical potentiometer, and is attached to the output rotation shaft 31a. A rotating slit plate 41 fixed concentrically to the outer periphery and a fixed position sandwiching it. A laser diode 42 and a semiconductor position detection element 43 arranged opposite to each other, A fixed slit placed between the rotary slit plate 41 and the semiconductor position detection element 43 It is composed of a top plate 44. The rotating slit plate 41 has the shape shown in FIG. In order to achieve rotational symmetry, an arc with an angle exceeding a certain angle of 2φ is stretched. A pair of fan-shaped portions 411 and 412 are formed. The angle 2φ is the electric This is the maximum rotation angle range of the machine. One fan-shaped portion 411 has an angle exceeding 2φ. A spiral light passing slit 413 is formed over the angle. This pickpocket The cut 413 is a part of a spiral centered on the center of the rotating slit plate 41. . Therefore, the radius vector r and the rotation angle Θ of the slit plate 41 are r=a−(δ/ 2π) Θ. Here, δ is the pitch of the helix. The rotating slit plate 41 When it rotates, the slit 413 also rotates, so the laser diode The position of this slit 413 facing the door 42 moves in the radial direction. child As a result, the light on the light receiving surface of the semiconductor position detection element 43 is transmitted through the fixed slit plate 44. By changing the light receiving position, it is possible to obtain an electrical signal corresponding to the rotation angle. example For example, as shown in Figure 5, it is possible to obtain an output voltage proportional to the rotation angle. . Here, the rotation angle of the electric motor 1 in this example is a maximum of 2φ, and is usually 20 or more. It is within a range of 30 degrees. Therefore, the value of δ/2π can be increased. This increases the resolution and enables highly accurate position detection.

0012 In the electric motor 1 of this example, the rotor 33 is initially set to the state shown in FIG. Ru. That is, the N pole 32S of the permanent magnet on the rotor 33 side and the fixed magnet on the stator side. The magnetic attraction force acting between the N pole 38N of the attached permanent magnet member 38 returns to the origin. The rotor 33 is in a state where it has returned to the origin position shown in the figure by acting as a force. It will be done. In this state, on the side of the position sensor 41, as shown in FIG. The center of the slit 413 of the rotating slit plate 41 is the laser diode 4. 2 and the semiconductor position detection element 43. In this state, the field control circuit A drive current is supplied to the field windings 343 and 344 via a path (not shown), and this As a result, the rotor 33 changes depending on the strength of the magnetic field formed between the stator and the rotor. rotates by a predetermined angle. Since the principle of generating such rotational driving force is well known, Detailed explanation will be omitted.

[0013] When the rotor 33 rotates by a certain angle in this way, it becomes fixed to the rotating shaft 31. The rotating slit plate 41 of the mounted position sensor 4 also rotates. As a result, Depending on the amount of rotation of the lit plate 41, the light receiving position on the semiconductor position detection element 43 side changes, and the output signal from there, for example, the value of the output voltage, changes as shown in Figure 5. Change. Therefore, the actual rotation angle position of the rotor can be detected from this change. . The magnetic field control circuit controls the drive current based on the detected actual rotation angle position. The generated magnetic field can be controlled and the rotor can be precisely positioned at the target rotation angle position. Wear.

[0014] Here, the permanent magnet member 38 for generating a restoring force attached to the stator side is always The rotor 33 is attracted. Therefore, the rotor always has a radial via. The rotational shaft is prevented from wobbling due to the force applied thereto. In addition, the field control circuit When the supply of drive current through the path is stopped, the rotor 33 moves to this permanent magnet member 38. The suction force causes it to return to its original position. In this way, in this example, The permanent magnet member 38 generates a force for returning the rotor to its origin, and also causes the rotor to return to its origin. It is also used to prevent shaft runout by applying a radial bias force. Ru.

[0015] Note that in this example, one permanent magnet member 38 is used to rotate the rotor. Although the magnet is biased in the radial direction, it is not possible to use multiple permanent magnet members. Can also be done. In addition, if there is no need to return the rotor to its home position, , it is also possible to use repulsive force instead of attractive force to bias the rotor in the radial direction. can. In addition, we also introduce rotary motors that are used not only in electric motors but also in other fields. The structure of this invention can be adopted for the purpose of preventing shaft runout. Of course.

[0016] In the position sensor 41 in this example, light passes through the rotating slit plate 411. However, instead of this, a light transmitting portion through which light passes is formed. may be formed. Alternatively, a light-reflecting portion may be formed to reflect light from the side of the light-emitting element. The light may be reflected here and received on the light receiving element side. Also, The shape of the rim is not limited to a spiral shape, but can be slit depending on the rotation angle. It may be of any shape as long as it allows the position to change.

[0017] As explained above, the electromagnetic limited rotation motor of this example uses permanent magnets. Since the rotor is made of ferromagnetic materials, The electromechanical conversion efficiency can be increased compared to the case where a rotor is used. Therefore, the generated torque can be increased.

[0018] In addition, a permanent magnet member is attached to the stator side, and this is used to locate the origin of the rotor. It is configured to generate both a return force and a biasing force in the radial direction.

[0019] Therefore, if these forces are generated using separate mechanisms, The structure of the electric motor can be simplified, and the device size can be made smaller and more compact. It can be done.

[0020] Furthermore, an optical pot with high detection accuracy is used to detect the rotational angular position of the rotor. Uses a rotation meter to accurately control the rotational angle position of the rotor. be able to.

[0021]

[Effect of the idea]

As explained above, in the present invention, the fixed A permanent magnet member is arranged at the position shown in FIG. Therefore, this permanent magnet allows the rotating shaft to is always biased in its radial direction. Therefore, with a simple configuration It is possible to prevent shaft runout due to rotational movement of the rotating shaft. In addition, the permanent magnet part If the magnetic force of the material is used to attract rotational force, this attraction force can be used to rotate the rotating shaft. As a returning force to return the permanent magnet member from the rotated state to the position where the permanent magnet member is placed. Available.

[Brief explanation of drawings]

FIG. 1 is an external perspective view showing an example of an electromagnetic limited-rotation electric motor incorporating a rotating shaft vibration prevention structure according to the present invention.

FIG. 2 is a schematic vertical sectional view of the electric motor in FIG. 1;

FIG. 3 is a schematic cross-sectional view of a portion taken along line III-III in FIG. 2;

FIG. 4 is an explanatory diagram showing a rotating slit plate that constitutes a position sensor in the electric motor of FIG. 1;

FIG. 5 is a graph showing an example of the relationship between the rotation angle and the output voltage in the position sensor of FIG. 1;

[Explanation of symbols]

1... Electromagnetic limited rotation electric motor 3...Electric motor body 31...rotation axis 31a...Rotation center axis 32...Permanent magnet 33...Rotor 34...Stator 341, 342...Magnetic pole part 343, 344...Field winding 35, 36...Bearing 38...Permanent magnet member 4...Position sensor

Claims (3)

[Scope of utility model registration request] 1. A rotating shaft having at least a portion of its outer peripheral surface made of a magnetic material, a bearing means rotatably supporting the rotating shaft over at least a certain angular range, and on the outer periphery of the rotating shaft, A structure for preventing shaft runout of a rotating shaft, comprising: a permanent magnet member that is disposed at a position facing the portion made of a magnetic material and generates a magnetic force that biases the rotating shaft in a radial direction. 2. The structure for preventing shaft runout of a rotating shaft according to claim 1, wherein an outer peripheral portion of the rotating shaft facing the permanent magnet member is made of a permanent magnet. 3. The structure for preventing shaft runout of a rotating shaft according to claim 1, wherein the magnetic force generated between the rotating shaft and the permanent magnet member is an attractive force.